There are many potential applications for surfaces with texture at the micro/nano scale. These applications include the electronics industry where surface texture can be applied to novel sensors and devices, the solar energy industry where surface texture plays an important role in adding to the efficiency of the solar cell, and the medical industry where textured surfaces play many important roles by providing hydrophobic and hydrophilic surfaces where cell growth can be controlled.
Lately surface texture has become a subject of much interest due to the phenomenal growth in the photovoltaic solar industry and by the drive for more efficient solar cells. Surface texture has also been demonstrated to increase the efficiency of the solar cell module. The addition of an anti-reflective surface (ARC) layer is typically deployed in addition to surface texture but even with these measures, reflection losses typically amount to 5-10 percent. Although there are other methods of inducing surface texture, surface texture is typically applied by use of a chemical isotropic or anisotropic etching process. This processing step is not only costly and time consuming, but also is ineffective for technologies other than mono-crystalline silicon. There is a need for a flexible, cost-effective approach to providing materials with the ability to reduce surface reflection of solar light that causes lower conversion efficiency.
There is also much interest in surface texture technologies for anti-icing applications in, for example, commercial and military airplanes, blades for wind energy generation, large refrigeration systems used in biomedical applications and many other industries. In the United States aviation industry alone, it has been estimated that over 25 million gallons of anti-icing chemicals are used annually at a purchase cost of $8-$12 per gallon, which does not include any costs related to environmental impact.
Boeing recently published a list of current alternatives being tested to reduce dependence on de-icing fluid, including special hangars with infrared heaters, truck-mounted infrared heater panels, forced hot-air systems, combination hot-air systems and de-icing fluids, and laser-based systems. There is a need for alternative, lower-cost methods. Ice formation is also a significant problem for wind energy generation as ice adds weight to blades that causes lower conversion efficiency as well as safety issues from flying ice debris. Wind power operators currently either accept the diminished efficiency of ice forming on their blades or they install shut off mechanisms to prevent the blades from rotating. Similarly, other industries which use large scale freezers must take steps to be certain that ice is removed on pipes and other structures. There is a need to develop a low-priced solution that would eliminate many of these problems associated with ice formation.
Recently work has been done producing anti-reflecting coatings by utilizing nanoimprint replication techniques to produce textured “moth-eye” surfaces. Whereas this method is simpler than the more traditional chemical etching techniques, there is need for an even simpler and cost-effective solution. A simple, cost-effective solution for surface texturing would allow for wider adoption of these technologies in various industries, and contribute to reduction in costs, enhanced efficiency from time savings, and the added benefit of enhanced safety in many applications.